Papermaking machine



Feb. 19, 1963 R. E. .GROBE ETAL 3,077,629

PAPERMAKING MACHINE File d Feb. 3. 1961 4 Sheets-Sheet 1 Feb. 19, 1963 R. E. GROBE ETAL PAPERMAKING MACHINE 4 Sheets-Sheet 2 Filed Feb. 3, 1961 ce' z 477 ll I" Feb. 19, 1963 R. E. GROYBE ETAL PAPERMAKING MACHINE 4 Sheets-Sheet 3 Filed Feb. 3. 1961 9 2 5 7 7 3 L A T E E B O R G E R 9 1. 0w 1. F

PAPERMAKING MACHINE I 4 Sheets-Sheet 4 Fil ed Feb. 3. 1961 United dtates Patent@ 3,077,629 PAPERMAKGNG MACHTNE Ralph E. Grebe, Appleton, and Clarence B. Allen, Neenals, Wis, assignors to Kimberly-{Bark Corporation, Neennl's, Wis, a corporation of Delaware Filed Feb. 3, 1961., Ser. No. 86,911 Claims. (Ql. 15-2565) The invention relates to papermaking machines and more particularly to apparatus for creping paper web from a heated drier drum.

A paper or tissue forming machine generally comprises a forming wire carrying the wet paper web which is couched from the wire and is partially dewatered between felts and which is subsequently pressed onto the surface of at least one drier drum. These drums may be heated by means of steam applied internally of them. In the case of a so-called Yankee type paper machine, only a single drum is used, and the wet paper Web is pressed onto the surface of the drum and is dried to the desired final moisture content within a single revolution of the drum. The Yankee machine differs from the conventional Pourdr-in'ier paper machine in that the latter has a number of small drier drums, and the paper is transferred from one drier drum subsequently to the others. The paper may be removed or creped from the large Yankee drier drum by means of a doctor blade which rides on the surface of the drum.

The present invention is concerned particularly with such doctor blades and apparatus for mounting the doctor blades. It has been found with such Yankee drier drums that a doctor blade causes greater wear on the outer surface of the drum beyond the edges of the paper sheet than in the middle region of the drum. It is, of course, desirable that the doctor blade extend beyond the sheet edges, particularly if the doctor blade is oscillated in its creping action. The doctor blades are generally of steel and the drier drums may be of cast iron, and these two materials are somewhat compatible for rubbing action between the two, inasmuch as there is a slight lubricating action between them. Nevertheless, there is some unevenness of wear due to doctor blade action. it has also been proposed to manufacture the drum of an aluminum bronze alloy, particularly of wrought sheets which are welded together to form the outer cylindrical part of the drum, in view of the fact that it is not practicable to cast or roll the cylindrical part of the drum as a single unit. Aluminum bronze is softer than cast iron, although it does transmit more heat than does cast iron, and, therefore, the wear is greater with such an aluminum bronze drum particularly between the edges of the web and the drum ends. There is also some unevenness of wear outside of the web in the vicinity of the welds, since, as a practical matter, it is not possible to provide welds with absolutely the same metal characteristics as the wrought sheets.

Generally speaking, undue wear does not occur on the drum surface of either the cast iron or aluminum bronze drier drums between the edges of the paper sheet, due apparently to the paper debris which is carried by the drum in the areas between the edges of the sheet and which has a slight lubricating action. This satisfactory wear condition between the web edges is due apparently also to the fact that the paper web in being creped from the drum has the action of tending to separate the doctor blade from its contact with the drum.

it is an object of the present invention to overcome such excessive and uneven wear in the end regions of such drums of cast iron or of softer material, such as the aluminum bronze; and we have found that this may be accomplished by reducing the pressure of the doctor blade on the drum end regions as compared to the blade pres sure in the drum areas between the edges of the web.

It is, therefore, another object of the present invention to provide an improved doctor blade and holding appara- .tus therefor which provides the reduced pressure on the end regions of the drums.

Briefly, a preferred form of our invention comprises a plurality of backing blades held by a holder in forceful contact with the doctor blade which is turn contacts a drier drum. In order to reduce the pressure of application of the doctor blade, the backing blades are cut off in the vicinity of the paper web edges; and, in addition, the holder for the doctor blade is arranged so that the doctor blade between the paper web edges and the ends of the doctor blade may have a limited swinging or rotation.

The invention consists of the novel constructions, arrangements and devices to be hereinafter described and claimed for carrying out the above stated objects, and such other objects, as will be apparent from the following description of preferred forms of the invention, illustrated with reference to the accompanying drawings, wherein:

FIG. 1 is a fragmentary side elevational view of a papermaking machine incorporating a drier drum doctor blade assembly embodying the principles of the invention;

FIG. 2 is a fragmentary end view on an enlarged scale of the machine and showing in particular the drier drum and doctor blade;

FIG. 3 is a fragmentary perspective end view on a still further enlarged scale of the doctor blade assembly;

FIGS. 4 and 5 are sectional views on a still further enlarged scale taken on lines 44 and 5-5 respectively of FIG. 3;

FIG. 6 is a view taken on line 6-6 of FIG. 4.

FIG. 7 is a view on an enlarged scale taken on line 7-7 of FIG. 5;

FIG. 8 is a sectional view of certain doctor blade supporting plates in the blade assembly; and,

FIG. 9 shows a modified form of doctor blade useable in the assembly.

Like characters of reference designate like parts in the several views.

Referring now to the drawings and in particular to FIGS. 1 and 2, there is illustrated fragmentarily a typical Yankee type paper machine, particularly the dry end of the machine, which includes a drier drum 10. The drum is supported by a supporting frame 11 resting on a suitable foundation 12. The wet paper web 13 is adapted to be applied to the outer surface of the drum having its edges 14 spaced a few inches, such as about 6 or 7 inches, from the edges of the drum and being dried by the drum during a single revolution thereof.

The drum 10 includes a generally cylindrical shell 15 which is fixed to heads 16. The drum is mounted for rotation by means of end shafts 17 disposed in bearings 18 secured to the frame 11. The drum 10 is rotated by a conventional driving mechanism (not shown)- which is attached to one of the shafts 17 by a suitable gear or pulley arrangement.

The drum 10 has steam supplied to it by conventional connections for heating the drum to dry the web 13, and additional heat for drying the web on the surface of the drum is provided by a heated hood 19 secured to the frame 11 and extending around the upper portion of the drum 10. Suitable hot air inlets and outlets are provided in the hood for the entry and discharge of the air or other heating medium.

The shell 15, as well as the heads 16, may be made of cast iron which is a conventional material for Yankee driers, or the shell 15 may be formed by means of a plurality of plates 15a welded together along seams Zll.

"suitable means (not shown).

The plates a and preferably the heads 16 also, may be formed of an aluminum bronze alloy which may have the specific compositions and which may be made in accordance with the metallurgical processes described in the co-pending application of John F. Klement for A Welded Wrought Aluminum Bronze Article and a Method of Heat Treating the Same, Serial No. 682,577, filed September 9, 1957 (now'Patent No. 2,937,965, issued on May 24, 1960). In brief, the alloy may con tain 5 to 8 percent of aluminum, .05 to 4 percent of iron, .01 to 5 percent of nickel, .01 to 5 percent of manganese, .01 to 2 percent of tin, .01 to 5 percent of zinc, and the balance of copper. The composition of the welding material for the seams is substantially the same as the plates 15a, having, however, a slightly greater amount of aluminum, such as 8 percent to 11 percent, in 'view of the fact that a small amountof aluminum is lost during the welding procedure. The plates 15a are wrought, that is rolled; while the other parts of the drurnlt) are cast.

The wet paper web to be dried is carried by a felt web 21 which travels" around rolls 22. The paper web is forced against the surface of the drum 19 by a pressure roller 23 which is rotatably mounted in brackets 24 attached to arms 25. The arms 25 are pivoted at 26 to the frame 11, .and the pressure roller 23 is forced against the surface of the drum 10 by rams 27 of hydraulic cylinders 23 which bear against the arms 25. The dried paper web is removed from the surface of the drier shell by a creping doctor 29 which includes a creping blade 30 secured within a doctor blade holder 31. The ends of the holder 31 are provided with shafts 32 which are rotatably mounted from within guide blocks 33. The blocks 33 in turn are each mounted within a slide assembly 34 attached to a pivot frame 35 pivotally carried by frame 11. The doctor blade holder 31 and the blade 30'are pivoted by a toggle mechanism 36 which is attached through a lever arm 37 to one of the shafts 32. In addition, a spring loading mechanism 38 of any suitable detailed construction is connected through the toggle mechanism 36 to provide a resilient contact for the doctor blade 30 against the surface of the drier drum 10.

In addition to the vertical and pivotal adjustment for the doctor blade 30, the doctor blade is adapted to oscillate in a direction parallel to the axis of the drum 10. The'oscillating motion is provided by an eccentric drive which is shown generally at 39 connected to one of the shafts '32. The oscillating motion is permitted by .aloose fit between the pivot frame 35 and the frame 11 and permits the doctor blade to move back and forth across'the surface of the drum 10 as the drum 10 rotates to prevent uneven'wear of the blade 30.

Referring to FIG. 3, the'doctor blade holder 31may be seen to comprise side support bars 40 and 41 on opposite-sides of the blade 30. A doctor blade support bar '42 is disposed between the bars 40 and '41, and the parts 40, 41 and'42 are fastened together at 'their'bases byfany suitable means (not shown) to act as a single assembly. The doctor blade-30 extends slightly beyond the ends "of the drum 10 and is substantially coincidental in length with the parts 40, 41 and 42.

Three backing blades 43, 44 and are provided behind the doctor blade 30 for supporting the doctor blade and causing-it to forcefully bear on the'outer surface of the'drum '10. The backing blades are fixed at their bases with respect to the parts 40 and 41 by any The backing blades 43, 44 and 45 are cut back in their'end regions, between about 4 inch and /2 inch outsideof the sheet edges 14 and the blade ends, so asto havezends 43a, 44a and 45a which are approximately coincidental with the end 40a of .thepart 40. The end surfaces 43:: and 44a are sub- .stantially-normal-to the blades 43 and 44, and the surface 45a is preferably chamfered, as illustrated 'in FIG. 5, at

anangle of about .30 degrees with respect to the fiat side of the part 45 adjacent the blade 39. As will be observed, the backing blades 43, 44 and 45 are progressively greater in length in the middle regions of the blades between the sheet edges 14, having respective ends 43b, 44b, and 45b, and extend closer to the doctoring edge 30a of the blade 30. The backing blade 45 between the edges of the sheet 13 is in contact and supports the doctor blade 30, and the blades 43 and 44 respectively are shorter than and bear on the blades 45 and 44 for the width of the sheet 13. The blade 45 is chamfered on its tip, as at 46, on its side adjacent the blade 36.

The backing blades 43, 44 and 45 are supported on their inner edges by a shoulder 41b. The blade support bar 42 has a plurality of square buttons 47 fixed to it forming the base of a groove '48 .for receiving'and supporting the lower edge of the doctor blade 30. The groove 48 has one side defined by a shoulder 42a. Slots 4? and 5! are provided in the backing blades44 and 45 receiving the buttons 47. The shoulder 42a of the groove 48 is removed, so as to provide a surface 42b that is flush with the upper surface of each 'of the buttons 47, from the ends of the bar 42 to points slightly beyond the edges 14 of the sheet 13. The bar 42 is 'chamfered at 51, below each edge 14 of the sheet 13, so as to allow a blade 30' to he slipped sidewise .into place for the purpose of changing blades 30.

In operation of the papermaking machine, the paper web is disposed on the lower pass of the felt 21 and travels with the felt around the lower felt roll 22 to the pressure roller 23, thepaper web transfers from the felt onto the outer surface of the drum10 and travels with the drum within the heating hood 19, so that the paper web is substantially completely dried between them by the time it reaches the doctor blade 30.

The doctor blade 30' scrapes or crepes the paper web from the exterior surface of the drum 1t}, and the paper web-is then rolled on suitable'rolls (not shown) for storage purposes. For securing the correct pressure of application of the doctor blade 30 on the drum surface 15, the spring loading mechanism 38.may be manually adjusted.

The doctor blade 30 is held in forceful contact with the external surface of the drum 10 between the edges 14 of the web 13 by means of the backing blades 43, 44 and 45. The blades 43-, 44, 45 and 30, particularly the latter, are flexible, and the blade 30 in particular is flexed due to the force of application to the drum 10. The doctor blade 39 is in effect stiffened considerably by the backing blades 43, 44 and 45 which extend beyond the end surface 40a just short of the doctoring edge 30a of the doctor blade 30 in the middle region of the blade 30.

It is desirable that the pressure of the blade 30 against the drum 10 on end regions of the drum, outside of the edges 14 of the paper Web 13, be considerably less than the pressure on the middle region of the drum, so that excessive wear does not occur. In order to provide this decreasing doctor blade pressure, the blades 43, 44 and 45 have been 'cut off substantially equal with the upper end 4021 of the support part 40', between the sheet edges 14 and the edges of the drum; and, therefore, the stiffening action of the backing blades 43, 44 and 45 is not effective in these end regions of the blade 30. In addition, theside42a of the-groove 48 has been removed so as to provide the surface 42b on the same level as the buttons 47 in end regions of the blade support bar 42. The doctor blade 30in these end regions thus may also have a twisting and pivoting action, its lower end moving to the left as seen in FIG. 5, over and on top of the surfaces 42b to further decrease the pressure of the blade 30 on the drum. In order to provide looseness for the blade 30 in these regions between the parts 4% and 41 to permit such pivoting action, the chamfered surfaces 45a have been provided on the backing blade 45. The chamfered edge portions 46 of the blade 45 are provided so that there is a gradual change of pressure of the doctor blade 30 on the drum at the sheet edges 14, these chamfered surfaces providing relief between the backing blade 45 and the doctor blade 30- at these points.

Since the pressure of application of the doctor blade 30 has been decreased from the sheet edges 14 to the ends of the drum 10 by means of the illustrated blade holding apparatus, the blade 30 does not cause undue wear on the drum in these end regions, even though the drum may be constructed of aluminum bronze and welded from wrought plates of this material instead of being a single casting of cast iron.

A modified form of doctor blade is illustrated in FIG. 9. The modified doctor blade 52 is ground out to have an indented lower edge 52a which is received within the blade holding assembly, and this surface 52a preferably is rounded as at 52!). Using the blade 52, the upper shoulder 42a of the blade support bar 42 need not be removed in the end regions, and the groove 48 in the bar 42 may be allowed to remain uniform from one end to the other of the bar. Since the doctor blade 52 is narrower in its end regions, the shoulder 42a does not restrict the blade 30 in the end regions, and the same pivoting action is obtained in the end regions as with the blade 30, with the edge 52a pivoting beyond and over the shoulder 42a.

We wish it to be understood that the invention is not to be limited to the specific constructions and arrangements shown and described, except only insofar as the claims may be so limited, as it will be apparent to those skilled in the art that changes may be made without departing from the principles of the invention.

What is claimed is:

1. In a doctor blade assembly, the combination of a flexible doctor blade, a plurality of backing blades extending alongside of said doctor blade, means for supporting said blades and including a pair of rigid support parts on opposite sides of said blades, said doctor blade protruding from between said rigid parts to have a doctoring edge and said backing blades also protruding from be tween said parts short of said doctoring edge to support said doctor blade and being cut back in end regions of the doctor blade so as to be farther from said doctoring edge in end regions of the doctor blade than in the middle region of the doctor blade so that the doctor blade may flex to a greater extent in its end regions than in its middle region.

2. In a doctor blade assembly, the combination of a flexible doctor blade, a plurality of backing blades behind the doctor blade for rigidifying the doctor blade, and a plurality of rigid blade support parts including one on each side of said blades for supporting the blades, one of said support parts having a groove for supporting the inner non-working edge of the doctor blade so that the inner edge of the blade and the groove form a tongue and groove arrangement, said backing blades being cut back along end regions of the doctor blade so as to be farther from the doctoring edge of the doctor blade in these regions than in the central region of the doctor blade and said tongue and groove arrangement being discontinued along the end regions of the doctor blade so that the doctor blade may flex to a greater extent and twist and swing in its end regions to have a decreased force applying eifect in its end regions than in its middle region.

3. In a doctor blade assembly, the combination of a flexible doctor blade, a plurality of backing blades behind the doctor blade for rigidifying the doctor blade and a plurality of rigid blade support parts including one on each side of said blades for supporting the blades, one of said support parts having a groove for supporting the inner edge of the doctor blade, said backing blades being cut back in end regions of the doctor blade so as to be farther from the doctoring edge of the doctor blade in these regions than in the central region of the doctor blade, the inner edge of said doctor blade along its said end regions being cut back so as to allow the doctor blade to twist and swing in the end regions of the blade between the support parts on the sides of the blades so that the doctor blade has a decreased force applying effect in its end regions than in its middle region.

4. In a doctor blade assembly, the combination of a flexible doctor blade, a plurality of backing blades behind the doctor blade for rigidifying the doctor blade, and a plurality of rigid blade support parts including one on each side of said blades for supporting the blades, one of said support parts including a groove in the part for supporting the inner edge of the doctor blade, said backing blades being cut back in end regions of the doctor blade to be farther from the doctoring edge of the doctor blade in these regions than in the central region of the doctor blade and a side of said groove along the end regions of the doctor blade being cut back to free the doctor blade from restraint and allow it to twist and swing in its end regions so that the doctor blade has a decreased force applying effect in its end regions as compared to its middle region.

5. In a doctor blade assembly, the combination of a flexible doctor blade, a plurality of backing blades behind the doctor blade for rigidifying the doctor blade, a pair of rigid support parts on opposite sides of said blades for supporting the blades, and a blade support bar between said support parts having a groove for receiving the inner non-working edge of the doctor blade and supporting the doctor blade, said backing blades extending outwardly beyond said support parts increasing distances for successive ones of the backing blades closer to said doctor blade and said backing blades being cut back to one of said support parts along end regions of said doctor blade, the said backing blade in contact with said doctor blade in said end regions having at least an outer region thereof of decreased thickness and said groove having a side thereof removed along said end regions so as to permit the twisting and swinging of said doctor blade in said end regions so that the doctor blade has a decreased force applying effect in its end regions as compared to its middle region.

References Cited in the file of this patent UNITED STATES PATENTS 2,330,889 Holcomb Oct. 5, 1943 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,077,629 February l9 1963 Ralph E. Grobe et all,

error appears in the above numbered pat- It is hereby certified that t the said Letters Patent should read as ent requiring correction and tha corrected below.

for -"is read in column 4 line Column 2, line 9,

At the pressure roller 23 a 32, after 23" insert Signed and sealedthis 24th day of September 1963.,

(SEAL) Attest:

DAVID L. LADD Commissioner of Patents ERNEST W. SWIDER Attesting Officer 

1. IN A DOCTOR BLADE ASSEMBLY, THE COMBINATION OF A FLEXIBLE DOCTOR BLADE, A PLURALITY OF BACKING BLADES EXTENDING ALONGSIDE OF SAID DOCTOR BLADE, MEANS FOR SUPPORTING SAID BLADES AND INCLUDING A PAIR OF RIGID SUPPORT PARTS ON OPPOSITE SIDES OF SAID BLADES, SAID DOCTOR BLADE PROTRUDING FROM BETWEEN SAID RIGID PARTS TO HAVE A DOCTORING EDGE AND SAID BACKING BLADES ALSO PROTRUDING FROM BETWEEN SAID PARTS SHORT OF SAID DOCTORING EDGE TO SUPPORT SAID DOCTOR BLADE AND BEING CUT BACK IN END REGIONS OF THE DOCTOR BLADE SO AS TO BE FARTHER FROM SAID DOCTORING EDGE IN END REGIONS OF THE DOCTOR BLADE THAN IN THE MIDDLE REGION OF THE DOCTOR BLADE SO THAT THE DOCTOR BLADE MAY FLEX TO A GREATER EXTENT IN ITS END REGIONS THAN IN ITS MIDDLE REGION. 